FR2935470A1 - THERMAL GENERATOR WITH MAGNETOCALORIC MATERIAL - Google Patents

Abstract

The present invention relates to a heat generator (1), constituted by at least one thermal module (2) integrating a magnetocaloric element (3) arranged between two hot (4) and cold (5) chambers, and crossed on both sides. by an incompressible heat transfer fluid via a first and a second circulation means (6, 7) each disposed in one of the hot (4) and cold (5) chambers, said heat generator (1) also comprising a magnetic arrangement arranged to alternately subject the magnetocaloric element (3) to a magnetic field variation and alternatively create in the magnetocaloric element (3) a heating cycle and a cooling cycle, a heat generator (1) characterized in that that the second circulation means (7) comprises a compensating member (8) allowing, on the one hand, during the displacement of the first circulation means (6) towards the magnetocaloric element (3), the displaces it said second circulation means (7) towards the end of the hot or cold chamber (4 or 5) concerned opposite to the magnetocaloric element (3) and secondly automatically returning the second circulation means (7). ) to the magnetic element (3) during the return of the first circulation means (6) to the end of the corresponding cold or hot chamber (5 or 4) opposite to the magnetocaloric element (3).

Description

TECHNICAL FIELD The present invention relates to the field of thermal energy generation and more particularly relates to a thermal generator with magnetocaloric element. This thermal generator is constituted by at least one thermal module integrating a magnetocaloric element disposed between two hot and cold heat chambers, said magnetocaloric element being crossed on both sides by a volume of incompressible heat transfer fluid, this volume of fluid being displaced by via a first and a second circulation means each disposed in one of the hot and cold chambers and each alternately returning the fluid to the opposite circulation means by reciprocating between the ends opposite of the corresponding hot or cold chamber. said thermal generator also comprising a magnetic arrangement arranged to alternately subject each magnetocaloric element to a magnetic field variation and alternatively create in said magnetocaloric element a heating cycle and a cooling cycle, generating the creation and then maintaining a gradient of temperature between the two opposite ends of said magnetocaloric element, the alternating displacement of the coolant being synchronized with the variation of the magnetic field.

PRIOR ART: Magnetic cold temperature at room temperature technology has been known for more than twenty years and we know the advantages it brings in terms of ecology and sustainable development. Its limits are also known as to its useful calorific power and its efficiency. Therefore, research in this area all tend to improve the performance of such a generator, by playing on the various parameters, such as the magnetization power, the performance of the magnetocaloric element, the exchange surface between the heat transfer fluid and the magnetocaloric elements, the performance of the heat exchangers, etc.

One of the difficulties in producing generators using one or more magnetocaloric elements resides in the exchange of thermal energy between these magnetocaloric elements and the circuit or circuits using, consuming or exchanging thermal energy with the generator, and connected thereto. generator. A solution for performing this exchange is to circulate a heat transfer fluid, liquid or not, through the magnetocaloric elements, in synchronization with the variation of the magnetic field to which the magnetocaloric elements are subjected.

In its French patent application No. 0707612, the Applicant presents a thermal generator magnetocaloric material in which the coolant is circulated between the magnetocaloric elements and two exchange chambers known as hot chamber and cold room. This circulation is achieved by means of two sets of pistons located opposite the magnetocaloric elements and driven by a control cam connected to an actuator.

This generator, however, has a disadvantage inherent in the need for two means for actuating the two sets of pistons located on either side of each magnetocaloric element. This causes an increase in the number of parts constituting the generator, and more particularly the number of moving parts and therefore an increase in the risk of malfunction, a risk of increased wear due to the permanent contact between the cam and the pistons, and degradation of the generator output. In addition, it poses sealing problems between the piston liner and the drive mechanism or the cam. SUMMARY OF THE INVENTION

The present invention aims to overcome these disadvantages by providing a thermal generator in which the number of actuating members or maneuvering means for the circulation of the heat transfer fluid is reduced.

For this purpose, it proposes a thermal generator of the kind indicated in the preamble in which the second circulation means comprises a compensation element allowing, on the one hand, during the displacement of the first circulation means towards the magnetocaloric element, the displacement in the same direction of said second circulation means towards the end of the corresponding hot or cold chamber remote from the magnetocaloric element and, secondly, automatically returning the second circulation means to the magnetic element when returning the first means circulating towards the end of the corresponding cold or hot chamber remote from the magnetocaloric element.

When the magnetocaloric generator according to the invention comprises more than one thermal module, the latter may be arranged adjacent to each other, preferably with the magnetocaloric elements aligned or arranged at the same level.

Thus, if it is considered that the first circulation means arranged on the same side with respect to the magnetocaloric elements form a set of circulation means, and the second circulation means form a second set, the first set is driven by a operating member and the second set comprises an automatic compensation member which allows it to move without the intervention of an operating member. This has the effect of a structural simplification of the heat generator. According to the invention, said compensation member of said thermal module can be integrated in the latter.

The invention also provides that said compensation member may simultaneously form the second heat transfer fluid circulation means.

In one embodiment, the compensation member may be able to compress under the force exerted by the heat transfer fluid during the displacement of the first circulation means towards the magnetocaloric element and to resume its initial shape upon the return of the first means. at the end of the corresponding hot or cold chamber opposite to or away from the magnetocaloric element.

This compensation member may be arranged between the second circulation means and the bottom of the corresponding hot or cold chamber. At the bottom of the chamber, it is necessary to understand the end of the chamber opposite to the magnetocaloric element.

According to the invention, said compensation member may be chosen from the group comprising the compression spring, the elastic buffer, a compressible fluid. As a variant, the compensation member may simultaneously form the second circulation means and comprise an elastic membrane fixed at the end of the corresponding hot or cold chamber situated on the side of the magnetocaloric element, so as to receive the heat transfer fluid at the outlet of the magnetocaloric element 25 from the cold or hot chamber opposite.

This elastic membrane is deformed by the force of the heat transfer fluid coming from the opposite cold or hot chamber and returns to its initial shape when the first circulation means is returned to the end of the hot or cold chamber opposite the element. magnetocaloric.

In another embodiment, the second circulation means can be realized, at least in part. in a magnetic material or comprise such a magnetic material and the compensation member may comprise a magnet of polarity identical to that of the magnetic material of the second circulation means and be integrated in or disposed at the bottom of the hot or cold chamber in which is disposed the second circulation means.

The second circulation means may be chosen from the group comprising a piston, an extensible membrane.

In another embodiment, the compensation member may comprise at least one fluid connection member between the volumes of the hot and cold chambers located behind the first and second circulation means with respect to the magnetocaloric element, this connecting member fluidic and these volumes forming a closed circuit filled with an incompressible drive fluid.

In addition, the fluidic connection member may incorporate a throttle for regulating the speed of the driving fluid and therefore that of the first and second circulation means.

Brief description of the drawings:

The present invention and its advantages will become more apparent in the following description of the embodiments given by way of nonlimiting example, with reference to the appended drawings, in which: FIGS. 1A and 1B are plan views of a thermal generator according to a first embodiment of the invention, representing the circulation means in their two extreme positions, - Figures 2A and 2B are views similar to those of Figures lA and 1B of a thermal generator according to a second embodiment, FIGS. 3A and 3B are views similar to those of FIGS. 1A and 1B of a thermal generator according to a third embodiment, FIGS. 4A and 4B are views similar to those of FIGS. 1A and 1B of a generator. according to a fourth embodiment, FIGS. 5A and 5B are views similar to those of FIGS. 1A and 1B of a thermal generator according to a fifth form of FIG. In the embodiment of the invention, FIGS. 6A and 6B are views similar to those of FIGS. 1A and 1B of a thermal generator according to a sixth embodiment of the invention, and FIGS. 7A and 7B are views similar to FIGS. those of Figures 6A and 6B of the thermal generator in which the compensation member comprises a choke.

Different Embodiments of the Invention In the exemplary embodiments illustrated, the identical parts or parts bear the same numerical references.

FIGS. 1A and 1B show a thermal generator 1 according to the invention 20 comprising two thermal modules 2 adjacent and superimposed, each integrating a magnetocaloric element 3 disposed between two hot and cold rooms 4 and 5 comprising a heat transfer fluid. A first circulation means 6 of the coolant is disposed in the hot chamber 4 and a second circulation means 7 is disposed in the cold chamber 5 or vice versa. The second circulation means 7 cooperates with a compression spring 8 forming a compensation member or return member. The compensation member may also be constituted by an elastic buffer or other similar means. The compression spring 8 is shown in transparency in FIGS. 1A and 1B. The physical parameters of the compression spring 8 such as the free length or the stiffness are determined so as to allow a progressive compression of the compression spring 8 under the pressure. the action of the pressure or force exerted by the heat transfer fluid when it is displaced by the first circulation means 6 and to achieve a compression preferably when the stroke of said first circulation means 6 is finished, namely when it is in abutment against the wall of the relevant chamber located at the level of the magnetocaloric element 3. Thus, the compression of the compression spring 8 allows the displacement of the heat transfer fluid through the magnetocaloric element 3 to the chamber in which is located the second means circulation 7, namely the cold room 5 in the example shown. When the first circulation means 6 returns to its initial position, the force exerted by the coolant on the compression spring 8 decreases until it disappears and the latter relaxes while automatically driving the second circulation means 7, and therefore the heat transfer fluid, in the opposite direction.

The alternating displacement of the heat transfer fluid in the thermal module 2 is thus obtained by an automatic compensation element 8 associated with the second circulation means 7 of the fluid and an operating member 11 controlling the displacement of the first circulation means 6. The chamber in which is positioned the second circulation means 7 is closed, it does not need to provide contact between the second circulation means 7 and an actuator, and any risk of leakage is avoided.

The heat generator 1 also comprises a magnetic arrangement (not shown) alternately subjecting each magnetocaloric element 3 to a magnetic field variation, and the alternating displacement of the coolant is synchronized with the variation of the magnetic field.

The magnetocaloric element 3 is permeable to the coolant and can be constituted by one or more magnetocaloric materials. It comprises opening fluid passages which may be constituted by the pores of a porous material, mini or micro-channels machined in a solid block or obtained by an assembly of superimposed grooved plates, for example.

The actuator 11 shown is a carriage disposed facing the hot rooms 4 in which are mounted the first circulation means 6, formed by pistons. These pistons 6 each include a magnet capable of interacting with magnets of different polarities mounted on or integrated in the carriage 11 which moves in front of the thermal modules 2 in a translational movement and back and forth represented by the double arrow 12.

Thus, in FIG. 1A, the carriage 11 is in a position which, on the one hand, pushes (towards the left in the figure) the piston 6 of the hot chamber 4 of the upper thermal module 2, which causes a displacement of the fluid to the cold chamber 5 and. the compression of the compression spring 8 and, on the other hand, attracts (to the right in the figure) the piston 6 of the hot chamber 4 of the lower thermal module 2, which allows the expansion of the compression spring 8 and a displacement or automatic return of the fluid to the hot chamber 4.

When the carriage 11 is translated, other magnets then interact with the pistons 6. Thus, in FIG. 1B, the carriage is in a position which, on the one hand, draws (towards the right in the figure) the piston 6 of the hot chamber 4 of the upper thermal module 2, which causes the expansion of the compression spring 8 and a displacement or automatic return of the fluid to the hot chamber 4 and, on the other hand, pushes (to the left on the FIG. 6) of the hot chamber 4 of the lower thermal module 2, which causes the fluid to move towards the cold chamber 5 and the compression of the compression spring 8.

A reciprocating movement of the coolant is thus obtained with a single operating member, the latter controlling only the circulation means located on one side of the thermal modules 2.

FIGS. 2A and 2B show a heat generator 10 also having a compression spring 8 (not represented in transparency through the pistons 7 forming the second circulation means) and in which the single actuator is made in the form of a control cam 13 driven by an actuator (not shown) and having a cam profile 14 of substantially sinusoidal shape whose amplitude determines the travel of the first circulation means 6 in the form of pistons. The operation of this thermal generator is similar to that described above.

The first and second circulation means 6 and 7 may have any shape allowing them to move the coolant, for example a piston or a membrane.

In the thermal generator 20 shown in FIGS. 3A and 3B, the actuating member of the first circulation means 6 is a carriage 11 such as that of the heat generator 1 of FIGS. 1A and 1B. With regard to the second displacement means 7, these also form a compensation member and are in the form of an elastic membrane 28 disposed in each hot chamber 4. This elastic membrane 28 is fixed at the end of said chamber which is located on the side of the magnetocalocaloric element 3, around the corresponding end of the magnetocaloric element 3, and is deformed under the pressure or force of the coolant coming from the opposite cold chamber 5 while receiving the coolant at the outlet of the magnetocaloric element 3 Then, upon the return of the first circulation means 6 to its initial position, the elastic membrane 28 returns to its original shape and pushes the fluid towards the cold room 5 opposite. The elasticity of the membrane 28 is chosen such that it allows a deformation of the membrane 28 under the pressure exerted by the fluid arriving from the opposite chamber, this deformation being sufficient to receive a volume of heat transfer fluid equivalent to the volume of the fluid moved in the cold room 5.

The heat generator 30 of FIGS. 4A and 4B also comprises an actuator in the form of a carriage 11. It nevertheless comprises a compensation element made by a magnet 38 arranged on the bottom of the hot chamber 4 and whose polarity is the same as that of the second circulation means 7 in the form of a piston. The displacement of the first circulation means 6 towards the magnetocaloric element 3 forces the displacement of the piston forming the second circulation means 7, this, against the repulsive force between the two identical poles, and the return of the first means displacement 6 in its initial position causes the displacement of the second circulation means 7 favored by the repulsion force between the two magnets, to the magnetocaloric element 3. Of course, we will choose a driving force of the first circulation means 6 greater than the repulsive force between the second circulation means 7 and the compensation member 38.

The generator 40 of FIGS. 5A and 5B also comprises an operating member in the form of a carriage 11. The compensation element of this generator is made in the form of a compressible gas introduced into the hot chamber 4 in which is the second circulation means 7 in the form of a piston, behind the latter with respect to the magnetocaloric element 3. This compressible gas 18 is compressed under the pressure of the coolant during the displacement of the first circulation means 6 towards the element magnetocaloric 3 pushing the heat transfer fluid to the hot chamber 4 and expands upon the return of said first circulation means 6 in its initial position, thereby pushing the heat transfer fluid through the magnetocaloric element 3 to the cold chamber 5.

FIG. 5A represents a state in which the gas 18 is compressed in the hot chamber 4 of the upper thermal module 2 and expanded in the hot chamber 4 of the lower thermal module 2. FIG. 5B represents an inverted situation after displacement of the operating member 11.30. FIGS. 6A and 6B show a heat generator 50 according to another embodiment in which the operating member is also in the form of a carriage 11 and the compensation member is in the form of a pipe 48 forming a fluidic connecting member connecting the volumes V1 and V2 of the hot and cold rooms 4 located behind the first and second circulation means 6 and 7 of the A same thermal module 2. The pipe 48 and these volumes VI and V2 contain an incompressible driving fluid which flows from one volume VI to the other volume V2 and vice versa during the displacement of the first circulation means 6.

With reference to FIG. 6A, when the first moving means 6 is moved towards the magnetocaloric element 3 (to the left in the upper thermal module 2), the coolant is pushed through the magnetocaloric element 3 towards the cold room 5, which has the effect, on the one hand, of pushing the second circulation means 7 towards the bottom of the cold chamber 5 and, on the other hand, of circulating the driving fluid of the volume V2 towards the volume V1 through line 48.

FIG. 6B shows, in the upper thermal module 2, the return of the first circulation means 6 in its initial position (to the right), which has the effect of driving the driving fluid from the volume V 1 towards the volume V 2 of the hot chamber 5, automatically driving the second circulation means 7 to the right.

It may further be provided to incorporate a choke 16 in the conduit 48, as shown in the heat generator 60 of Figures 7A and 7B. This heat generator 60, which has the same configuration as the heat generator 50, makes it possible, by virtue of the choke 16, to adjust the speed of displacement of the driving fluid, and therefore the speed of movement of the first and second circulation means. 6 and 7. This also makes it possible to determine the passage time of the heat transfer fluid through the magnetocaloric element 3 and thus to make maximum use of the heat properties of the latter.

Although all the figures represent a linear thermal generator, the invention also applies to a thermal generator of circular configuration in which the thermal modules 2 are arranged in a circle around a central axis, or in any other configuration. The invention applies to any generator in which each thermal module 2 comprises a first heat transfer fluid circulation means 6 operated by any type of control member or maneuver, and a second circulation means 7 which comprises or integrates a compensating member 8, 18, 28, 38, 48 according to the invention allowing it to move in an alternating movement from one end position to the other in the chamber, so as to print an alternating circulation to the fluid of the part and on the other hand and through the magnetocaloric element 3.

In addition, and as already indicated, the compensation member 8, 18, 28, 38, 48 may be disposed in or at any of the hot and cold rooms 4 and 5.

Possibilities of industrial application: It is clear from this description that the invention makes it possible to achieve the goals set, namely to propose a magnetocaloric generator 1, 10, 20, 30, 40, 50, 60 of simple construction limiting the number of operating elements for the circulation of the heat transfer fluid in the thermal modules 2 through the magnetocaloric element 3, limiting the risks of loss of tightness of the magnetocaloric generator and increasing its service life.

Such a heat generator 1, 10, 20, 30, 40, 50, 60 can find an industrial as well as domestic application in the field of heating, air conditioning, tempering, cooling or other, this, at competitive costs and in a small footprint.

In addition, all the components of this heat generator 1. 10, 20, 30, 40, 50, 60 can be made according to reproducible industrial processes.

The present invention is not limited to the embodiments described but extends to any modification and variation obvious to a person skilled in the art while remaining within the scope of protection defined in the appended claims.

Claims (11)

Revendications1. Thermal generator, constituted by at least one thermal module (2) integrating a magnetocaloric element (3) disposed between two hot (4) and cold (5) thermal chambers, said magnetocaloric element (3) being crossed on either side by a volume of incompressible heat transfer fluid, this volume of fluid being displaced via a first and a second circulation means (6, 7) each disposed in one of the hot (4) and cold (5) chambers and each alternately returning the fluid to the opposite circulation means (7, 6) by reciprocating between the opposite ends of the corresponding hot or cold chamber (5), said heat generator (1 ) also comprising a magnetic arrangement arranged to alternately subject each magnetocaloric element (3) to a magnetic field variation and alternatively to create in said magnetocaloric element (3) an oscillation cycle uffement and a cooling cycle, generating the creation and maintenance of a temperature gradient between the two opposite ends of said magnetocaloric element (3), the alternating displacement of the heat transfer fluid being synchronized with the variation of the magnetic field, thermal generator (1 , 10, 20, 30, 40, 50, 60) characterized in that the second circulation means (7) comprises a compensating member (8, 18, 28, 38, 48) allowing, on the one hand, during the moving the first circulation means (6) towards the magnetocaloric element (3), moving in the same direction of said second circulation means (7) towards the end of the corresponding hot or cold chamber (4 or 5) remote from the magnetocaloric element (3) and, on the other hand, automatically returning the second circulation means (7) to the magnetic element (3) during the return of the first circulation means (6) to the end of the chamber cold or hot (5 or 4) c corresponding distant from the magnetocaloric element (3). 14 2. Thermal generator according to claim 1, characterized in that said compensating member (8, 18, 28, 38) of said thermal module (2) is integrated in the latter. 3. Thermal generator according to claim 2, characterized in that said compensation member (28) simultaneously forms the second circulation means (7) coolant. 4. Thermal generator according to any one of claims 2 and 3, characterized in that the compensation member (8, 18) is adapted to compress under the force exerted by the coolant during the movement of the first means of flow (6) to the magnetocaloric element (3) and to return to its initial shape upon the return of the first circulation means (6) at the end of the hot or cold chamber (4 or 5) corresponding remote from the magnetocaloric element (3). 5. Thermal generator according to claim 4, characterized in that the compensation member (8, 18) is arranged between the second circulation means (7) and the bottom the corresponding hot chamber (4) or cold chamber (5). . 6. Thermal generator according to claim 5, characterized in that the compensation member is selected from the group comprising the compression spring (8), the elastic buffer, a compressible fluid (18). 25 7. Thermal generator according to claim 3, characterized in that the compensation member simultaneously forms the second circulation means (7) and comprises an elastic membrane (28) fixed at the end of the hot or cold chamber. (4 or 5) corresponding to the side of the magnetocaloric element (3), so as to receive the heat transfer fluid at the outlet of the magnetocaloric element (3) 30 from the cold or hot chamber (5 or 4) opposite. 20 8. Thermal generator according to any one of claims 1 and 2, characterized in that the second circulation means (7) is made, at least in part, of a magnetic material or comprises such a magnetic material and in that the compensation member comprises a magnet (38) of the same polarity as the magnetic material of the second circulation means (7) and is integrated in or disposed at the bottom of the hot or cold chamber (4 or 5) in which the second circulation means (7) is arranged. 9. Thermal generator according to any one of claims 1 to 6 and 8, characterized in that the second circulation means (7) is selected from the group comprising a piston, an extensible membrane. 10. Thermal generator according to claim 1, characterized in that the compensation member comprises at least one member (48) for fluid connection between the volumes (V 1 and V 2) of the hot (4) and cold (5) chambers. located behind the first and second circulation means with respect to the magnetocaloric element (3), this fluidic connection member (48) and these volumes (V i and V2) forming a closed circuit filled with an incompressible drive fluid . 11. Thermal generator according to claim 10, characterized in that the fluidic connection member (48) incorporates a choke (16).